Add Fibonacci problem variant

Author: khairalanam

L-B/0020 NthFibonacciNumberO(1)/NthFibonacciNumberO(1).js

@@ -0,0 +1,11 @@
+const NthFibonacciNumber = (n) => {
+  root_five = Math.sqrt(5);
+  major_term = (1 + root_five) / 2;
+  minor_term = (1 - root_five) / 2;
+
+  return Math.round(
+    (1 / root_five) * (Math.pow(major_term, n) - Math.pow(minor_term, n))
+  );
+};
+
+module.exports = NthFibonacciNumber;